If you have more time, consider visiting other popular attractions like Fort St. George, Mahabalipuram, or the Thousand Lights Mosque. If you have less time, you can skip St. Thomas Mount and spend more time at Marina Beach or the Government Museum. Don't forget to carry a hat, sunglasses, and sunscreen, as Chennai can get quite hot and humid. Also, keep in mind that most attractions close by 5 pm, so plan your itinerary accordingly.